Loose-fill insulation has long been used as thermal insulation above ceilings, in wall cavities and in other areas of residential and commercial buildings. In general, the thermal efficiency of loose-fill insulation is inversely correlated to its density. The ideal loose-fill insulating products of this type consist of a material with small, uniform air pockets resulting in a low settled density insulation that resists the transfer of temperature and sound by direct conduction or convection of the air in the medium. A lower density insulation generally results in a product that provides the benefits of less material, less insulation weight requiring less building structural strength, and less installation time.
Loose-fill insulating material is normally installed in an attic or wall, using equipment for separating the fiber clumps and transporting the material in an airstream. The insulating product is blown between the attic joists in walls and in other locations. This process tends to aerate and fluff the insulation material, prior to it being placed into the space being insulated. After installation there is some settling of the insulation material, largely due to its own weight and internal structure, and also as a result of vibration and other outside forces.
Many attempts have previously been made to improve the efficiency and performance of insulation. For example, Smith, in U.S. Pat. No. 4,468,336, discusses the advantages of mixing a synthetic staple fiber with the loose-fill cellulose to lower the settled density of the resulting insulation. Smith proposed adding 2% to 25% polymeric staple fibers, having a denier between 1.8 and 60 and a fiber length between 4 and 20 mm, to cellulose. Smith teaches that the settled density of the resulting insulation product improved from 2.5 pounds per cubic foot for cellulose only, to 1.1 to 2.1 pounds per cubic foot for the mix insulation. Smith claims that the resulting product has less weight to fill a space, is less expensive to manufacture per unit of volume, and requires less structural support.
Helmstetter, U.S. Pat. No. 5,453,119 discloses the use of cotton and other fibers, including waste fibers obtained from discarded clothing, carpet, and the like. Helmstetter addresses the problem of increasing the insulating material's resistance to decay, and reducing the amount of free fibrous particles that may escape from the insulating material during handling. It does not deal with the problem of increasing loft when used in combination with other cellulosic materials such as reclaimed newspaper. Other patents relate to the application of a fire retardant to the cellulosic insulation material.
Despite the extensive effort in this area previously expended, a continuing need exists for an insulating material that provides a combination of minimal weight, ease of manufacture using conventional equipment, reduced dust, and compliance with applicable building codes and other regulatory standards.